Hair straightening has been used by many ethnic populations to produce a smoother texture and straighter appearance for more than 100 years. The initial method for straightening involved hot irons and coating the hair in petroleum. The result of this xe2x80x9cstraighteningxe2x80x9d process often resulted in burning the hair off. If not, this produced xe2x80x9cstraightxe2x80x9d hair styles which were short and over time caused the hair to break, resulting in shorter more brittle hair. This effect was amplified as straightening products were repeatedly used in the hair. The first commercial products, which have been available for over 70 years, were based on sodium hydroxide. While the amount of sodium hydroxide in the products has decreased over the years, the chemistry involved, and the methodology used has changed little over the years. Newer fixatives and conditioners have improved the texture of the hair to prevent some of the dry and brittle appearance that often results after long periods of using straighteners. However, the ability to grow long hair while straightening is still a difficult beauty challenge.
For the consumer with naturally curly hair, from a style perspective, the consumer either elects to have their hair xe2x80x9cnaturalxe2x80x9d leaving the curly texture of the hair as it is, or to use straightening products and have their hair xe2x80x9cstraightxe2x80x9d without curl. The current commercial products do not provide the consumer the option to have a hair style which is xe2x80x9cin betweenxe2x80x9d. An active life style which adds perspiration to the straightened hair can cause the relaxed hair to be dry, brittle and unmanageable. Extended use of the available straightening products can damage and weaken the hair resulting in hair that is short and brittle with little control.
There are two types of hair straightening products currently available in the U.S. cosmetic market. The first class is those based on a caustic xe2x80x9clyexe2x80x9d formulation. The products in this class are sometimes labeled as xe2x80x9clyexe2x80x9d or xe2x80x9cno lyexe2x80x9d. The lye based products contain the active ingredient sodium hydroxide. This chemical is very alkaline and is the same ingredient contained in drain cleaners. Other products in this class are referred to as xe2x80x9cno lyexe2x80x9d but only contain a different positive cation with hydroxide producing the same class of alkali chemical. The most common are calcium hydroxide and potassium hydroxide. Calcium hydroxide is often used in plaster and cement, while potassium hydroxide can be extremely corrosive. These formulas are commonly used in the commercially available hair straighteners bought for home use. These products are easy to apply and have a long history of use. As strong alkali products, these formulations can cause severe burns and are very hazardous to skin scalp and mucus membranes. These products carry specific label warnings to avoid contact with the skin.
The second class of products are ammonium thioglycolate based, often referred to as xe2x80x9cthioxe2x80x9d straighteners or xe2x80x9cpermsxe2x80x9d. These products are also alkaline and are most commonly used by professional beauticians. Without careful use by a professional, these products can be a depilatory in addition to causing severe bums. This product was originally developed from the permanent wave.
Both of the current straightening methods work in the hair essentially the same way. Both classes soften the hair and cause a swelling action to the shaft, sometimes up to three times the diameter of the hair. The product penetrates into the cortical layer and the cross bonds of sulfur and hydrogen are broken. The action of the combs and or hands smoothing the hair distributes the chemicals and straightens the softened hair. The hydroxide content ranges between 2 and 10 percent and produces a pH of greater than 10 (often as high as 12 or 13). In the hair this is considered to be a strong alkali. The higher the pH the faster the chemical reaction initiates hair straightening, the greater the softening of the hair and the greater the damage that can be done to the hair. Ammonium thioglycolate works essentially the same way with a less dramatic action than the hydroxide based formulas, and is assumed by the cosmetologist to be gentler to the hair.
One particular drawback of the current commercial products is that they are caustic in nature, with a pH of greater than 10, which weakens the hair shaft and causes hair damage. Specifically, the pH of hair varies over the length of the strand between about 4.9 and about 6.2, with more acid at the scalp than at the tips of the hair. Disulfide bonds are not permanently affected at pH levels between 2 and 6, but salt bonds can be affected at pH levels below 4. This is why typical caustic prior art straighteners operate at pH levels above 10. The hair cannot buffer itself against pH changes, so it is important to control pH within a specified range in order to maintain effectiveness of the hair treatment product and prevent permanent hair damage. As hair cannot regenerate, only grow out, permanent damage to the hair can affect the individual for a long period of time.
Since hair in its normal state is slightly acidic, the use of an acid to straighten hair should provide more protection to the hair. Other attempts have been made to produce a product having an acidic pH. However, previous acid-based compositions change the color of light hair, such as blonde hair or grey hair, to either green or black. The hair can also be xe2x80x9cbleachedxe2x80x9d out leaving it dry and brittle.
Additionally, traditional straightening compositions cause lanolization, i.e., produce hair that is permanently chemically altered and unable to reform the natural bonds. This process compromises the strength of the hair in order to produce the straight look. As a result, the hair cannot later be easily or safely styled with curls because the hair has lost its resilience. Further, traditional straightening products cause a permanent change in the hair chemistry, producing hair that is completely straight.
Further, traditional thio straightening product have a strong negative odor. The odor is difficult to mask, even with the addition of fragrance. Many consumers liken it to xe2x80x9crotten eggsxe2x80x9d.
The present invention is directed to a curl relaxation composition that attempts to overcome the above drawbacks. Instead of having a caustic or alkali formulation, the inventive composition is based on an acidic preparation that uses the natural hair chemistry to produce a more gradual and gentle straightening while adding combability and manageability to the hair. Additionally, the composition does not alter the natural color of the hair, even when applied to light hair, allowing safe application of the composition to red, blonde and grey hair.
Moreover, the composition does not chemically alter the hair. When applied to the hair, the inventive composition is at a pH that is slightly below the isoelectric point of keratin, the predominant protein in hair. This will temporarily break the disulfide and hydrogen bonds in the hair. This reaction, in combination with covering the hair during processing and smoothing the hair, will produce a straighter, more manageable appearance. When neutralized with a neutralizing shampoo, the disulfide bonds are restored and the hydrogen bonds are restored to the preferred a form, providing strength and durability during styling. The a form also provides shine and luster for the hair. The composition causes a permanent change in the curl of the hair without changing the hair chemistry. As a result, the composition of the present invention gradually relaxes the hair with repeated applications, allowing for more styling freedom. The inventive composition allows the hair to be safely smoothed and styled with curls while conditioning the hair for manageability and bounce. The hair has a more manageable texture, and the work required for combing decreases. This decreases mechanical damage to the hair, allowing its to remain healthier.
Further, preferred compositions in accordance with the invention are substantially odorless. Fragrances can be added to enhance the scent of the composition, but fragrance is not required to mask a negative odor associated with the composition.
In one embodiment, the invention is directed to a hair relaxation composition comprising an activator containing a thiosulfate compound, an acidifier, and a catalyst. The composition has a pH ranging from about 3.0 to about 4.5.
In another embodiment, the invention is directed to a hair relaxation composition comprising an activator containing a thiosulfate composition, an acidifier that does not impart a color change to the hair, and a catalyst.
In yet another embodiment, the invention is directed to a method for relaxing hair comprising applying to the hair one of the compositions described above.
In a particularly preferred embodiment, the invention is directed to a method for relaxing hair comprising applying to the hair one of the compositions described above. The composition is allowed to remain on the hair for a period of time ranging from about 10 minutes to about 60 minutes. The composition is then removed from the hair in a neutralizing process. The application, standing and removal steps are then repeated.
The present invention is directed to a composition and method for gradually relaxing hair. In one embodiment, the invention is directed to a composition comprising an activator containing a thiosulfate compound, an acidifier, and a catalyst.
The activator containing a thiosulfate compound is the active ingredient in the composition. The thiosulfate compound provides the necessary free sulfur for restructure of the disulfide bonds in the hair, allowing smoothing of the hair with a salt form that is most compatible with the hair. Preferred thiosulfate compounds include sodium thiosulfate, potassium thiosulfate and calcium thiosulfate. The activator is preferably present in an amount ranging from about 2% to about 35% by weight, more preferably from about 4% to about 10% by weight, based on the total weight of the composition.
The acidifier can be any suitable acidifier. Preferably the acidifier is a composition that does not impart a color change to the hair, such as citric acid or acetic acid. Suitable acidifiers for use in the inventive composition include citric acid, acetic acid, adipic acid, ascorbic acid, tartaric acid and tannic acid. The acidifier is present in the composition in a positive amount, preferably up to about 1.0% by weight based on the total weight of the composition. More preferably the acidifier is present in an amount ranging from about 0.2% to about 0.5% by weight based on the total weight of the composition. The acidifier is preferably provided in an amount such that the final composition has a pH ranging from about 3.0 to about 4.5, more preferably from about 3.3 to about 3.8.
A catalyst is provided in the composition to initiate the chemical reaction, allowing for the change in the disulfide bonds. As discussed in more detail below, prior to use, the catalyst is maintained separate from the activator, as is known in the art. The catalyst can be any suitable catalyst known to those skilled in the art. Preferably the catalyst is a chloride compound, such as zinc chloride, manganese chloride, or magnesium chloride, all minerals found naturally in hair. Preferably the catalyst is selected so as not to impart a color change to the hair and to be compatible with hair chemistry. The catalyst is present in the composition in a positive amount, preferably up to about 1.5% by weight based on the total weight of the composition. More preferably the catalyst is present in an amount ranging from about 0.2% to about 0.5% by weight based on the total weight of the composition. The amount of catalyst is selected based on the weight of the activator.
The composition preferably further comprises a filler to impart texture and thickness to the composition. The filler can be any suitable filler such as, for example, corn starch, talc, maltrin, carboxymethylcellulose gum or carboxyethylcellulose gum. Preferably the filler is present in the composition in an amount ranging from about 5% to about 40% by weight, more preferably from about 15% to 25% by weight, based on the total weight of the composition. As would be recognized by one skilled in the art, the amount of filler can vary as desired to provide the desired feel for the composition, which can be in any suitable form, such as liquid, gel, cream or paste form. Depending on the filler used, a thickening agent may be added to form the creme for the application texture. The application texture is a human factor consideration for easy application.
Additionally, the composition can contain any other suitable additives typically used in hair care compositions. Examples of such additives include, but are not limited to, fragrances, biocides (such as propylparaben), and fungicides (such as methylparaben), and nutrients (such as ascorbic acid and Vitamin E).
The remainder of the composition is water. As is known in the art, such compositions are traditionally provided in powdered form, with two distinct components so that the catalyst is separate from the activator. All ingredients are carefully blended and provided with a particle size sufficient to form a consistent powder that is easily hydrated in water. The powdered components can be combined together with water prior to use to form a composition of the desired consistency for the consumer.
The invention is also directed to a method for gradually relaxing, and optionally straightening, hair. According to the method the hair is cleaned and separated into sections. If desired, conditioner is applied at the hair line to prevent irritation, although the inventive composition is not particularly irritating, and thus conditioner is not necessary. Working with each section of hair individually, the user applied hair relaxation composition described above to the hair from root to end with the finger tips or a comb, spreading the mixture uniformly until all of the hair is saturated. After application, the hair is positioned as straight as possible, with longer hair being wrapped around the head. After the head is completely covered with the relaxation composition, it is covered with a plastic shower cap. Application time will vary depending on the porosity of the hair, as would be recognized by one skilled in the art, but is generally between about 20 and 60 minutes, preferably between 30 and 50 minutes. Typically, after 50 minutes the catalyst is used up, and thus further application time has little if any effect.
The hair is then rinsed thoroughly with warm water. During application with the inventive composition, the pH of the hair, which is normally between 5.5 to 6.0, is lowered to about 3.5 to 4. Accordingly, the hair is washed with a neutral pH balancing shampoo to restore the hair""s natural pH. The pH balancing shampoo should have a pH ranging from about 5.5 to about 7.0, preferably from about 5.5 to 6.5, which is close to the hair""s natural pH. If the shampoo has a higher pH, e.g., greater than 7.0, it can cause the hair to become brittle, or even break the hair. A suitable shampoo for use in accordance with the invention is Copa pH Balancing Shampoo, commercially available from Copa (Irvine, Calif.). Preferably a conditioner, optionally one with a compatible pH balancing effect, is also applied to the hair and allowed to remain on the hair for about 3 to 5 minutes.
The hair is then dried, either naturally or with a controlled moderate heat dryer. During the drying process, the hair can be stretched for further straightening, or curlers can be applied to style the hair.
Due to time constraints, preferably no more than two applications of the relaxation composition are initially applied. The first one to two applications condition the hair and provide a conditioned wave. If a straighter style is desired, additional applications can be provided. Preferably, three to five applications are provided. Further applications should be provided to new hair growth approximately every four to six weeks; however, for new hair growth only one application is typically necessary because the composition is concentrated on a smaller section of hair. During this reapplication, the inventive composition will not harm the old hair growth, on which it was previously applied.